Appeal — TEST-CLAIM-00094

Date: [Date of Submission]

Appeals and Grievances Department
Synthetic Aetna
[Payer Address]

Re: Formal Appeal of Claim Denial
External Claim ID: TEST-CLAIM-00094
Service Date: February 23, 2026
Denial Date: May 11, 2026
Denial Code: CO-198
Procedure Code(s): CPT 28818
Diagnosis Code(s): S82.00, F32.45
Billed Amount: $3,469.82
Denied Amount: $2,292.73

Dear Synthetic Aetna Appeals Department,

This letter constitutes a formal appeal on behalf of [Facility Name] regarding the denial of the above-referenced claim (TEST-CLAIM-00094) for services rendered on February 23, 2026. Synthetic Aetna issued a denial on May 11, 2026, under denial code CO-198 (Precertification/Authorization Exceeded), resulting in a denied amount of $2,292.73. We respectfully contest this denial and request that the claim be reprocessed and payment issued in full for the denied amount.

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I. BACKGROUND AND BASIS FOR DENIAL

The denied claim pertains to CPT code 28818 (ankle arthroscopy/endoscopy with treatment) performed on February 23, 2026. Synthetic Aetna has denied $2,292.73 of the total billed amount of $3,469.82, citing CO-198, which indicates that the services rendered exceeded the scope or dollar limit of the prior authorization on file. Our facility obtained a valid prior authorization prior to the performance of this procedure. We maintain that the authorization obtained was sufficient to cover the services as rendered, and/or that the clinical scope of the procedure — as dictated by intraoperative findings — fully justified any work performed beyond the initially authorized parameters, warranting retroactive authorization expansion.

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II. GROUNDS FOR APPEAL

A. Valid Prior Authorization Was Obtained

As evidenced by the enclosed prior authorization approval letter and the payer's prior authorization request form with approved authorization limits, a valid authorization was secured in advance of the February 23, 2026 procedure. Our facility fulfilled its obligation to obtain precertification in accordance with Synthetic Aetna's prior authorization scope/amount limitation requirement. The existence of an approved authorization on file undermines the basis for a CO-198 denial and suggests that any discrepancy in authorized limits may reflect an internal processing issue or an unduly restrictive interpretation of the original authorization.

B. Clinical Findings at Time of Service Justified the Full Scope of Work Performed

The enclosed operative report for CPT 28818 and the enclosed surgeon's documentation of clinical findings at the time of service demonstrate that the full scope of the ankle arthroscopy procedure was clinically necessary and directly responsive to the patient's diagnosed conditions. Intraoperative findings frequently reveal pathology that exceeds the scope anticipated at the time of the original authorization request. In such circumstances, it is well-established that payers should give appropriate deference to the treating surgeon's real-time clinical judgment. Any work performed beyond the initially authorized parameters was necessitated by the patient's clinical presentation, not by an administrative oversight on the part of our facility.

C. Medical Necessity Supports the Services as Billed

The enclosed letter of medical necessity provides a detailed clinical justification for the procedure as performed, including the full scope of treatment required on February 23, 2026. The diagnoses on file (S82.00, F32.45) further corroborate the clinical rationale for the procedure. Denial of payment for medically necessary services that were performed pursuant to a valid authorization — or that required clinically unavoidable expansion of scope — is inconsistent with Synthetic Aetna's coverage obligations.

D. Retroactive Authorization Expansion Is Warranted

To the extent Synthetic Aetna determines that the originally approved authorization limits did not encompass the full scope of services rendered, we respectfully request retroactive expansion of the authorization to cover the services as documented. The enclosed correspondence reflecting any verbal pre-approvals or authorization modifications further supports this request. Retroactive authorization is an appropriate remedy when intraoperative clinical circumstances necessitate services beyond those anticipated at the time of the original request, and when the provider acted in good faith reliance on an existing authorization.

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III. SUPPORTING DOCUMENTATION ENCLOSED

The following documents are enclosed in support of this appeal:

1. Prior authorization approval letter
2. Operative report for CPT 28818 (service date: February 23, 2026)
3. Letter of medical necessity explaining the scope of the procedure
4. Payer's prior authorization request form with approved authorization limits
5. Surgeon's documentation of clinical findings at time of service
6. Correspondence reflecting any verbal pre-approvals or authorization modifications

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IV. REQUESTED REMEDY

Based on the foregoing, we respectfully request that Synthetic Aetna:

1. Overturn the CO-198 denial issued on May 11, 2026, with respect to Claim TEST-CLAIM-00094;
2. Reprocess the claim to recognize the full scope of services rendered on February 23, 2026, under CPT 28818 as authorized and medically necessary; and
3. Issue payment of the denied amount of $2,292.73 in accordance with the applicable contracted rate and plan benefits.

This appeal is being submitted in advance of the applicable appeal deadline of November 7, 2026. We request written confirmation of receipt of this appeal and written notification of the appeal determination upon completion of review.

Should Synthetic Aetna require any additional clinical documentation or clarification, please do not hesitate to contact our billing and appeals department at [Facility Contact Information].

We appreciate your prompt attention to this matter and look forward to a favorable resolution.

Respectfully submitted,

[Authorized Facility Representative Name]
[Title]
[Facility Name]
[Facility Address]
[Facility NPI]
[Phone Number]
[Date]